Aims: The aim of the paper was to assess the importance of 24 h electrocardiographic Holter monitoring in determining predictive factors for Adams-Stokes (AS) attacks and heart failure (HF) in children and adolescents with complete congenital atrioventricular block (CCAVB).
Methods and results: Forty-five patients were divided into two groups according to the presence of AS attacks and HF and six age-related subgroups. The following parameters of 24 h electrocardiographic Holter monitoring were analysed: (i) minimum heart rate (HR), (ii) maximum HR, (iii) average HR, (iv) daytime HR (v) rhythm and conduction disturbance. Adams-Stokes attacks and HF occurred in 10 and 8 patients, respectively (40%). Five of six neonates with HF had maximum HR < 74 bpm and daytime HR < 58 bpm. Maximum HR below 68 bpm and daytime HR below 52 bpm were recorded in all the children up to 8 years of age with AS attacks and HF and only in 3 of 14 asymptomatic patients. All the patients above 8 years of age with AS attacks had maximum HR below 62 bpm. Of 6 patients with daytime HR < 50 bpm AS attacks were present in two. Episodes of marked ventricular slowing during sleep were registered in 4 of 10 (40%) patients and in 3 of 27 (11%) symptomless patients.
Conclusion: Risk factors for development of AS attacks and HF in patients with CCAVB include: (i) maximum HR < 74 bpm in neonates, <68 bpm up to the age of 8 and <62 bpm at ages above 8, (ii) daytime HR <58 bpm in neonates and < 52 bpm till the age of 8, and (iiii) abrupt pauses in ventricular rate that are at least twice the basic cycle length after the neonatal period.